1. Field of the Invention
The present invention relates to an air conditioning apparatus for a vehicle, which includes a heating heat exchanger and electric heating members integrated with the heating heat exchanger. More particularly, the present invention relates to a control unit for controlling a heat-radiating amount of the electric heating members and an amount of air blown from a blower.
2. Description of Related Art
In recent years, it is desired to improve an efficiency of an engine in an engine compartment. When the efficiency of the engine is improved, load applied to the engine is decreased, and cooling water for cooling the engine can not be sufficiently heated. Therefore, in a hot-water type air conditioning apparatus where air blown into a passenger compartment is heated using the engine cooling water, there is a problem that heating capacity for the passenger compartment is insufficient.
In a conventional heating device described in JP-A-9-20129, an electric member is attached to an air-flow inlet surface of a heating heat exchanger, and electric power is supplied to the electric member when the temperature of hot water flowing into the heating heat exchanger is low. Further, temperature of a passenger compartment and passed time after turning on the electric member are measured, and heat-radiating amont of the electric member is gradually decreased as the temperature of the passenger compartment and the passed time are increased. However, in the conventional cooling device, because a large amount of air is blown into the passenger compartment, the temperature of air blown into the passenger compartment is not increased sufficiently in cold winter even when the heat-radiating amont of the electric member becomes maximum.
On the other hand, in the conventional heating device, because the electric member is attached to the air-flow inlet surface of the heating heat exchanger, heat generated from the electric member is transmitted to hot water (engine-cooling water) flowing in the heating heat exchanger, and air passing through the electric member is not effectively heated by using heat generated from the electric member. Thus, the temperature of air blown into the passenger compartment is not heated sufficiently quickly using the electric member.